Surface Morphology and Carbon Incorporation for Hexagonal GaN/(111)B GaAs Metalorganic Vapor Phase Epitaxy Using Dimethylhydrazine and Trimethylgallium

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Abstract
Using dimethylhydrazine (DMHy) as a group V source, we grew hexagonal GaN layers on (111)B GaAs substrates by low-pressure metalorganic vapor phase epitaxy. The surface morphology of the hexagonal GaN layers and the carbon incorporation in them strongly depend on the V/III ratio and the reactor pressure. A flat GaN surface can be obtained at the V/III ratio of 60 and the substrate temperature of 850° C. The carbon concentration decreases with increasing reactor pressure and the minimum concentration is 2×1019 cm-3 for hexagonal GaN grown at 300 Torr. Low-temperature photoluminescence measurements reveal that the band edge emission for the GaN grown at 300 Torr is dominant compared with that of a deep level.